The present invention generally relates to internal combustion engines including electric starting systems and outdoor power equipment powered by such engines, such as lawn mowers, snow throwers, portable generators, etc. More specifically, the present invention relates to small internal combustion engines including electric starting systems powered by a removable, rechargeable lithium-ion battery.
Outdoor power equipment includes lawn mowers, riding tractors, snow throwers, pressure washers, portable generators, tillers, log splitters, zero-turn radius mowers, walk-behind mowers, riding mowers, industrial vehicles such as forklifts, utility vehicles, etc. Outdoor power equipment may, for example use an internal combustion engine to drive an implement, such as a rotary blade of a lawn mower, a pump of a pressure washer, the auger a snowthrower, the alternator of a generator, and/or a drivetrain of the outdoor power equipment.
Many pieces of outdoor power equipment include engines that are manually started with a recoil starter. To start the engine, the user must manually pull a recoil starter rope.
Other pieces of outdoor power equipment include electric starting systems in which a starter motor powered by a battery starts the engine. Typically, such electric starting systems also include a user-actuated starter switch (e.g., a pushbutton or key switch) and a starter solenoid. The starter solenoid is the connection between a low current circuit including the starter switch and a high current circuit including the starter motor. To start the engine, the user actuates the starter switch, causing the starter solenoid to close so that the battery provides starting current to the starting motor to start the engine.
The battery is a lead-acid battery. The battery is secured to the outdoor power equipment separate from the engine. For example, the battery may be secured to a mounting plate or deck of a lawn-mower or a pressure washer or to the frame of a riding lawn mower or a portable generator. The housing of the battery is secured to the outdoor power equipment by fasteners that require tools (e.g., a wrench or socket) to attach the battery to the outdoor power equipment and to remove or loosen the fasteners so the battery can be removed from the outdoor power equipment. Also, the battery includes a pair of terminals to which electrical leads are attached. Tools are also required to attach and remove the electrical leads to the terminals. Lead-acid batteries are filled with a liquid electrolyte, typically a mixture of water and sulfuric acid. The electrolyte is corrosive. Lead-acid batteries are temperature sensitive, which may result in the engine having difficulty starting or not starting at all in cold weather. Also, a lead-acid battery will run down with the passage of time and not be able to provide power (i.e., lose charge or become completely discharged). A lead-acid battery may need to be replaced seasonally, removed from the outdoor power equipment and stored inside, or otherwise maintained or serviced by a user.